Compound steam-engine.



PATENTED MAR. '7, 1905.

W. A. DREWETT.

COMPOUND STEAM ENGINE.

APPLIGATIOH FILED JAN.25,1904.

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PATENTED MAR. 7, 1905.

W. A. DREWETT. COMPOUND STEAM ENGINE.

APPLICATION FILED JAN-25,1904.

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No. 784,254. PATENTBD MAR. 7, 1905. W. A. DRBWETT.

COMPOUND STEAM ENGINE.

APPLICATION FILED JAN.26,1904.

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00977225585. fill/11101: 0 .4 /[u%w//y. W Y Z No. 784,254. Patented March 7, 1905.

UNITED STATES PATENT OFFICE.

XVILLIAM A. DREWVETT, OF NEWV YORK, N. Y., ASSIGNOR TO MARSHALL T. DAVIDSON, OF BROOKLYN, NEXV YORK.

COMPOUND STEAM-ENGINE.

SPECIFICATION forming part of Letters Patent No. 784,254, dated March '7, 1905. Application filed Iannary 25, 1904. Serial N0. 190,555.

TO 107107 it i l 0071667771: terior to the cylinder 1, so that the pressure 5 Be it known that I, IV ILLIAM A. DREWETT, a applied upon the two pistons will be transcitizen of the United States, and. a resident of mitted to the work, as is usual. the borough of Brooklyn, in the city and State The exhaust from the primary cylinder 1 is 5 of New York, have invented a new and useful transmitted, through a pipe 11, to a receiver Compound Engine, of which the following is 12, the connection with said receiver 12 being 55 a specification. in the present instance at the side of 'the re- My invention relates toa compound engine, ceiver near one end. The particular form of with the object in view of providing means receiver which I have illustrated in Figs. 1 to for maintaining the pressure in the secondary 3, inclusive, is provided with a nest of tubes cylinder at working efiiciency during the in- 13 for reheating the exhaust-steam within the 6 tervals when the engine is stopped and to furreceiver 12, and to this end the receiver is' ther provide for utilizing the secondary cylinprovided with hollow head portions 1 1 15, into der as a primary cylinder under conditions of one of which in the present instance 15 the 15 emergency when the engine may be called steampipe 16 from the boiler delivers the upon temporarily to do unusual work. steam, which is deflected from the upper por- 5 I A practical embodiment of my invention is tion of the head 15 by means of a diaphragm represented in the accompanying drawings, in 17 into the upper tubes of the nest 13 and which transmitted by them to the head 14:, from which Figurel is a view of the engine in side eleit is directed, by means of a diaphragm 18,

vation, partly in section. Fig. 2 is an end through other tubes of the nest into the head 70 elevation, partly in section, looking toward 15 below the diaphragm 17 and is in turn dethe right, the part section being taken in the flected into other tubes by means of the diaplane of the line A A of Fig. 1. Fig. 3 is an phragm 19 and caused to pass back again into 2 5 end elevation, partly in section, looking tothe head 14 belowxthe diaphragm 18, from ward the left, the part section being taken in where it is again deflected by the diaphragm 75 the plane of the line B B of Fig. 1; and Fig. 20 into other tubes of the nest 13 back to the 4 is a longitudinal section showing a modified head 15 at a point below the diaphragm 19, form of receiver. from which it escapes through a pipe 21. This 0 The engine to which my invention may be arrangement for reheating mayor may not be applied may either be single-cylinder or duused in connection with the other features of plex and may be applied to diflerent uses in my invention, but is found in practice to be the art, the particular type of engine which important under certain conditions. In the I have taken to illustrate my invention in the event this reheating of the exhauststeam 3 5 accompanying drawings being a form which within the receiver is not provided for the reis well adapted to pumping in connection with ceiver may take the form shown in Fig. 1, 8 5 elevator service. where it is denoted by 22 and where the ex- The primary cylinder is denoted by 1 and haust-pipe 11 from the cylinder 1 connects the secondary cylinder by 2. These cylinders with it in substantially the same position as are provided with the usual valve-chambers, that already described. Where this form of the valve-chamber upon the cylinder 1 being the receiver shown in Fig. 4 is employed, the 9 denoted as a whole by 3 and the valve-chamhollow heads, with their diaphragms, are not her upon the cylinder 2 being denoted by 4. needed, and the interior of the receiver may The valves for the two cylinders are connectbe left free from obstruction other than the ed, as is usual, by a rod 5 to work simultanewater-guard 23. I

ously, and the piston 6 in the cylinder 1 is The exhaust-steam from the cylinder 1 at'- provided with a central piston-rod 7, to which ter entering the receiver 12 passes along the the two piston-rods 8 and 9 of the piston 10 receiver to the pipe 2%, through which it is of the cylinder 2 are connected at a point exdelivered into the valve-chambera of the secondary cylinder 2. Any of the exhaust-steam which becomes condensed during the passage of the steam through or While it remains in the receiver 12 is prevented from entering the pipe 24 by means of a Water-guard 23, extending transversely across the bottom of the receiver, and is led from the receiver 12 through an opening 25 in the bottom of the receiver to a trapped Water-discharge pipe.

One of the important features of my present invention is the maintaining of a steampressure Within the receiver 12 or 22 corresponding to the Working pressure of the exhaust-steam from the cylinder 1 in order that the engine may be started at any moment after an interval of rest under full working pressure upon the pistons in both the primary and secondary cylinders. To provide for this,- a pipe 26, leading from the boiler or from some pipe in connection with the boiler, as may be found most convenient, is connected with the receiver 12 or 22 and is provided with a reducing pressure-valve 27 of any wellknown or approved form for automatically maintaining the pressure Within the receiver 12 at anydegree which may be determined upon within the range of the original boilerpressure. This reducing pressure-valve 27 is set to Work automatically to shut ofl the admission of steam from the boiler whenever the pressure within the receiver 12 reaches a point above the minimum Working pressure desired for the secondary cylinder and to open and admit steam from the boiler into the receiver 12 whenever the pressure within the receiver 12 reaches a degree below the minimum working pressure required of the secondary cylinder 2. In this manner the engine is at all times ready to start under full working pressure even though the load be greater than that which the piston and pressure in the primary cylinder is calculated to perform, since the maintenance of the pressure in the receiver will provide for utilizing the piston in the secondary cylinder to complete the power required. For instance, if the load required to be moved by the engine be a hundred pounds and the pressure and piston surface of the primary cylinder be calculated to perform seventy-live pounds and the secondary cylinder twenty-five pounds so long as the pressure in the receiver is maintained at twenty-five pounds the engine will be in position to start the load.

Should the pressure in the receiver fall below twenty-five pounds, as mi ht happen during an interval of rest by the entire or partial condensation of the steam therein, then the engine would be stalled and would have to be operated by some mechanical means for one or more strokes until the working efliciencyof the exhaust-steam in the receiver had been reached, and it is to overcome any such annoying and objectionable feature that my present invention is directed, and this it accomplishes by the means hereinabove described for automatically maintaining the. pressure within the receiver up to its required Working efficiency.

In the event the engine is to be employed temporarily for moving an unusually-heavy load at an unusual expenditure of steam I provide for using the secondary cylinder 2 as a primary cylinder by admitting steam under full pressure into the receiver 12as, for example, by a branch pipe 28 connecting with the main steam-pipe 29 and with the receiver 12, the said branch pipe 28 being provided with a valve 30 and the pipe 29 with a valve 31. When the secondary cylinder is so used as the primary cylinder, the piston in the primary cylinder 1 would work idly under a balanced pressure equal to the pressure of the steam in the secondary cylinder 2.

WVhat I claim is 1. The combination with a primary and a secondary cylinder, their pistons, a piston-rod to which the two pistons are connected and suitable valve gear, of a receiver through which the exhaust-steam passes from the primary to the secondary cylinder and automatic means for maintaining the pressure o1 the steam in the receiver at a predetermined degree While the engine is at rest.

2. The combination With the primary and secondary cylinders, their pistons, a piston-rod to which the tWo pistons are connected and the receiver, of a pipe leading from a steam-supply to the receiver and a reducing pressurevalve in said pipe for automatically maintaining the pressure of steam in the receiver at a pedetermined degree while the engine is at rest.

3. In a compound engine, the combination with a high-pressure cylinder and a low-pressure cylinder, of a receiver into which said high-pressure cylinder normally exhausts to thereby maintain suflicient pressure to actuate the piston of the low-pressure cylinder and means for automatically maintaining said pressure in said receiver when the engine is at rest.

Intestimony that I claim the foregoing as my invention 1 have signed my name, in presence of two Witnesses, this 5th day of January, 1904.

- WM. A. DREWETT. Witnesses:

FREDK. HAYNES, HENRY THIEME. 

